1. If a bridge or bridges be necessary over any river, stream or watercourse forming the boundary line or part of the boundary line between the state of Missouri and any adjoining state or states, the county commissions of the counties of this state bordering on such river, stream or watercourse may unite with such adjoining state or the proper authorities of any county in such adjoining state for building such bridge or bridges and the expense thereof shall be defrayed by such county of this state and the adjoining state or county therein in such proportion as may be agreed upon.

2. The plans and specifications for such bridge or bridges shall be prepared and the contract let and construction supervised by some competent person who may be agreed upon by the respective interested authorities; provided, that private subscriptions may be received by the county commissions of such counties in this state to defray in part or in whole the expenses of building such bridge or bridges; provided further, that for the purpose of defraying the expenses of building such bridge or bridges, or to create a fund with which to build any such bridge in the future, it shall be the duty of the county commission in such county in this state, upon a petition signed by a majority of the taxpaying citizens of any township in which such bridge is located or is to be located, to levy on the taxable property in such township the full amount of the special road and bridge tax authorized by the first sentence of the first paragraph of Section 12, Article X of the Constitution of Missouri, and use the same solely for the purpose of defraying the expense of building such bridge or bridges or creating a fund for the future building thereof, and such fund, when inaugurated, shall be perpetuated until such bridge or bridges are built and the cost thereof is defrayed.

3. The county commission may appropriate moneys from the road and bridge fund of the county to pay the cost or part of the cost of building such bridges.